Canopy feed method and apparatus for a trim press

ABSTRACT

The feeding of plastic sheet material to a trim press is carried out utilizing an endless belt conveyor which supports and drives the plastic sheet in a manner which is coordinated with the cycle of drawing of the sheet material into the trim press dies. The surface of the conveyor belt supports the plastic sheet for upward movement with little or no dragging of the sheet material, and the position of the plastic sheet being engaged with the conveyor can be set by an operator utilizing guide plates and guide wheels located at a position near the intake end of the conveyor. The conveyor belt may be driven continuously at a rate corresponding to the rate at which plastic sheet is drawn into the trim press, or in intermittent motion by a motor in a manner that is coordinated with the intermittent feeding of the sheet material into the trim press.

FIELD OF THE INVENTION

[0001] This invention pertains generally to the field of plasticthermoforming equipment and to feeding of thermoformed plastic sheetmaterial.

BACKGROUND OF THE INVENTION

[0002] In the thermoforming or vacuum forming process for producingplastic articles, a continuous sheet or web of thermoplastic is advancedin a step-wise fashion through a thermoforming machine wherein a sectionof the web is heated to soften it and then drawn into a mold. Theplastic sheet assumes the form of the mold, cools and hardens.Generally, the multiple individual plastic parts formed in this manner,such as the common “clamshell” plastic containers, must be cut from thesurrounding plastic web material. The formed plastic parts are typicallycut from the surrounding sheet in a separate trim press in which theplastic sheet is advanced, section by section, to be engaged by acutting die which cuts the formed parts out of the surrounding sheet.The trim press typically has an advancement mechanism which engages theplastic sheet to pull each formed section in a step-by-step fashion tothe position of the cutting dies.

[0003] In one common arrangement for feeding the formed plastic sheetinto the trim press, the continuous plastic sheet is drawn upwardly ontoa curved canopy formed of guide rods and then vertically downwardly intothe trim press. The typical stationary canopy is formed of guide rodswhich laterally orient the position of the plastic sheet so that it isin proper position to be engaged by the driving mechanism within thetrim press. The plastic sheet may be driven up the stationary guide rodsby rollers driven by a motor controlled by a limit switch. The limitswitch is tripped to turn off the motor driven rollers when a section ofsheet is discharged from the canopy that corresponds to the length ofsheet that will be drawn into the trim press.

[0004] Because the width of the formed plastic sheet and the position ofthe formed parts in the sheet may vary from one production run toanother, the position of the guide rods must be manually adjusted foreach production run. The manual adjustment of the positions of the guiderods is relatively time consuming, commonly requiring 45 minutes to anhour and a half depending on whether guide rods need to be added orremoved. The adjustment of the guide rods also requires the operator toclimb to the top of the trim press to reach all of the guide rods, aphysical requirement that although necessary with conventional equipmentwould preferably be avoided. Other functional disadvantages ofconventional stationary guide rods have been observed, including theformation of scratches on the plastic sheet as it is dragged along thestationary guide rods, the presence of plastic dust generated from thesliding plastic, and the potential buckling of thin gauge plastic sheetas it is pulled and then released by the driving mechanism within thetrim press. Various designs have been proposed for assisting the feedingof the sheet into the trim press using an oscillating or reciprocatingtype canopy, for example, as shown in U.S. Pat. Nos. 4,306,474,4,360,139, and 4,380,183. However, canopy arrangements with stationaryguide rods continue to be utilized with standard commercial trimpresses.

SUMMARY OF THE INVENTION

[0005] In accordance with the invention, feeding of plastic sheetmaterial to a trim press is carried out utilizing an endless beltconveyor which supports and drives the plastic sheet material being fedto the trim press in a manner which is coordinated with the cycle ofdrawing of the sheet material into the trim press dies. The surface ofthe conveyor belt supports the plastic sheet material for upwardmovement with little or no dragging of the sheet material across theconveyor surface, thereby minimizing scratching of the plastic materialand the generation of plastic dust. The conveyor also serves to drivethe plastic sheet material up to a discharge position above the trimpress rather than requiring that the plastic sheet be pulled by theforce of the trim press drive mechanism, reducing stretching of theplastic sheet as compared with conventional stationary canopy guides,and reducing the load imposed on the drive mechanism within the trimpress. Adjustment of the position of the plastic sheet being engagedwith the conveyor can be easily set by an operator at a position nearthe bottom or intake end in a quick and convenient manner, minimizingthe labor involved in setup and reducing setup time to a few minutes.The apparatus of the invention may be constructed to be set up by anoperator without requiring any tools.

[0006] A canopy feed apparatus in accordance with the invention includesframe members forming a frame, an endless belt conveyor mounted to theframe having a conveyor belt with a top facing side extending from anintake end to a discharge end, and a motor connected to the belt todrive the belt. When the apparatus is mounted to feed a trim press, theconveyor extends upwardly from its intake end to its discharge end witha plastic sheet exiting from the discharge end guided by guide rodsdownwardly into the trim press. The conveyor belt may be drivencontinuously to discharge plastic sheet continuously at a ratecorresponding to the average rate at which the plastic sheet is drawninto the trim press. The conveyor belt may also be driven inintermittent motion by the motor in a manner that is coordinated withthe intermittent feeding of the sheet material into the trim press. Thecoordination of the conveyor belt motion with the trim press feeding maybe carried out utilizing means for detecting a plastic sheet extendingoutwardly from the discharge end of the conveyor belt a selecteddistance and for controlling the motor of the conveyor to shut off powerto the motor when a section of plastic sheet exiting from the conveyorextends more than the selected distance from the discharge end. Themeans for detecting can include a limit switch with a trip rod extendingtherefrom that is mounted such that the trip rod is positioned to becontacted by a section of plastic sheet discharged from the conveyor.The excess plastic sheet exiting from the discharge end of the conveyorbulges out until it reaches the selected distance from the dischargeend, at which time the power to the motor for the conveyor is cut off,stopping the conveyor. When the trim press then operates to draw asection of plastic sheet downwardly into the trim press, the excessplastic sheet material is drawn away from the trip rod, resulting in theconveyor motor being turned on and the conveyor belt being driven tofeed additional plastic sheet material until the excess material againreaches the trip rod to turn off the conveyor. A blower may be mountedunder the conveyor at the discharge end to blow air outwardly to drivethe excess plastic sheet outwardly into contact with the trip rod of thelimit switch. The feeding of the plastic sheet from the conveyor in thismanner is fully coordinated with the drawing of the plastic sheet intothe trim press, so that substantially no strain is imposed on theplastic sheet being fed into the trim press, while at the same timeavoiding over-feed of plastic sheet from the conveyor which mightinterfere with the sheet feeding process.

[0007] Setup of the feed apparatus may be carried out quickly andconveniently utilizing a pair of guide plates and guide wheels mountedfor lateral adjustment over the top surface of the conveyor belt at aposition near the intake end of the conveyor. Preferably, a pair ofmounting bars extend laterally between frame members above the topfacing side of the conveyor belt, and the guide plates and guide wheelsare mounted for sliding movement on the mounting bars while restrainingthe guide plates and guide wheels from movement in other directions. Ahand operated clamp and a locking mechanism for each guide plate andguide wheel may be utilized by the operator to lock the guide plates andguide wheels at selected lateral positions at which the guide plates arespaced apart a distance equal to the width of the sheet being fed, andsuch that the sheet being fed will reach the trim press at the properlateral position. The guide wheels may be mounted for movement towardand away from the top surface of the conveyor, with an air cylinder ateach guide wheel being utilized to selectively press the guide wheelinto engagement with the plastic sheet supported on the surface of theconveyor.

[0008] Curved guide rods are preferably mounted at the discharge end ofthe conveyor and extend above and below the position of plastic sheetexiting from the discharge end of the conveyor to guide the plasticsheet downwardly to a proper position for feeding into the trim press.

[0009] Further objects, features and advantages of the invention will beapparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the drawings:

[0011]FIG. 1 is a partially cut away perspective view of a canopy feedapparatus in accordance with the invention mounted in a position to feedplastic sheet material to a trim press.

[0012]FIG. 2 is a side view of the canopy feed apparatus of theinvention.

[0013]FIG. 3 is a partial view of the intake end of the canopy feedapparatus of the invention.

[0014]FIG. 4 is a partial detailed view of the intake end of the feedapparatus showing the mounting of guide plates and guide wheels abovethe top surface of the conveyor.

[0015]FIG. 5 is a partial perspective view of the discharge end of thefeed apparatus of the invention.

[0016]FIG. 6 is a schematic diagram of the control and drive circuit forthe feed apparatus for the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] With reference to the drawings, a canopy feed apparatus for atrim press in accordance with the invention is shown generally at 10 inFIG. 1, mounted adjacent to and in position to feed a continuous sheetor web 11 of thermoformed plastic material into a trim press 12. Theplastic sheet 11 typically has a series of parts 14 formed therein whichare surrounded by the original sheet material and from which the parts14 are to be cut in the trim press 12. The parts 14, which are formed ina conventional thermoforming apparatus (not shown), extend outwardlyfrom a side of the sheet 11 opposite a flat side 15 as illustrated inFIG. 1. The trim press 12 may be any of the various conventional trimpresses that are utilized for trimming formed plastic parts and will notbe described further herein.

[0018] The feed apparatus 10 includes a rigid frame 18 formed of framemembers (e.g., of conventional structural steel) to which an endlessbelt conveyor 20 is mounted. The frame 18 serves to provide a structuralsupport for the various parts of the apparatus and may be formed in anydesired shape or construction to serve that purpose. For purposes ofexemplifying the invention, the frame 18 as shown in the drawingsincludes two parallel main beams 21, two main vertical beams 22 whichextend downwardly from one end of the main beams 21, and two lateraldescending beams 24 which extend downwardly and outwardly from the otherends of the main beams 21 opposite that to which the vertical beams 22are joined. A cross beam 25 extends between and is secured to the twomain beams 21 and, as best shown in FIG. 2, braces 27 extend downwardlyfrom the main beams 21 to bases 28 which are fixed to the bottoms of themain vertical beams 22. The beams 21, 22, 24, 25, 27 and 28 are rigidlyjoined together by, for example, welding, to form a rigid structure. Theconveyor 20 is mounted to the frame 18 at a lower end 30 of the lateraldescending beams 24 and to the braces 27 at an upper position 31 of theconveyor 20. The conveyor 20 is an endless belt conveyor having rigidstationary side rails 32 which are connected to the frame members at thepositions 30 and 31 by, for example, being secured thereto with bolts(not shown).

[0019] The conveyor 20 has an endless conveyor belt 33 that extends froma roller 34 at an intake end 35 of the conveyor to a roller 36 at adischarge end 37, with the endless belt 33 having a top facing side 39and a bottom side 40. The conveyor belt 33 may be formed of a flexiblematerial, e.g., various synthetic plastics, that is strong and durableand has a desired fairly high coefficient of friction with respect tothe plastic material of the bottom surface 15 of the plastic sheet 11.An example of a suitable commercial conveyor is the 3100 Series conveyorfrom Dorner Manufacturing Co. (Hartland, Wis.), preferably with a highcoefficient of friction belt approved by the FDA for use with packagingfor foods (e.g., /O3 Soft Top FDA with urethane surface and polyesterbody). Crossbars 42, as shown in FIG. 1, may extend between the siderails 32 and be secured thereto to rigidify the conveyor structure. Asshown in FIG. 2, an electric motor 44 (preferably including a speedreducing gearbox) is connected by a belt 45 to the upper end roller 36to drive the belt 33 when the motor 44 is supplied with electricalpower. For example, a DC motor may be used with a gear reducer (e.g.,Tigear 60 to 1 gear ratio from Dodge Gearbox). The conveyor extendsupwardly at an angle to horizontal (e.g., about 30° and preferably 28°)from the intake end to the discharge end.

[0020] As best shown with reference to the views of FIGS. 3 and 4, apair of mounting bars 47 extend laterally above the top surface 39 ofthe conveyor belt and are mounted at their ends to brackets 50 which aresecured (e.g., by welding) to the lateral descending beams 24. A ruler48 is preferably mounted in front of the lower bar 47. A pair of slidebearings 51 slide on the uppermost one of the mounting bars 47 and areconnected to brackets 52 which support one end each of a pair of guideplates 54. Another pair of slide bearings 51 are also mounted to slideon the second mounting bar 47 and support slide clamps 55 which eachhave a hand operated locking mechanism 56 by which the operator can lockthe slide clamps 55 in place on the lower mounting bar 47. The slideclamps 55 have brackets 58 connected thereto which are each connected tothe forward end of one of the guide plates 54. A pair of guide wheels 60are mounted for rotation to brackets 62 which are themselves pivotallyconnected to the brackets 52. Air pressure driven air cylinders 64 areconnected at one end to the brackets 52 and at the other end to thepivoting brackets 62. When supplied with air under pressure, the aircylinders 64 extend to drive the guide wheels 60 downwardly into contactwith a plastic sheet supported on the top surface 39 of the conveyor.The lateral guide plates 54 serve to properly position the incomingplastic sheet as it reaches the intake end 35 of the conveyor so thatwhen the sheet exits the conveyor it will be properly positionedlaterally to be fed appropriately into the trim press. To adjust thelateral position of the guide plates 54, the operator turns the handlesof the locking mechanisms 56 on the clamps 55 to release the engagementof the clamps with the lower mounting bar 47 and then moves the guideplate 54 to a desired lateral position, at which the operator turns thehandle on the locking mechanism 56 to clamp the guide plate 54 and theguide wheel 60 carried with it in the proper lateral position. Thespacing between the two lateral guide plates 54 is selected to match thewidth of the plastic sheet being fed. To aid the operator in properlypositioning the lateral guide plates, the ruler 48 preferably includesindicia 66 marked on a front face thereof which represent a distancescale (e.g., inches or centimeters, preferably as a half scale forconvenience) which can be correlated by the operator with the clamp 55to determine the lateral position of the clamp from one edge of theconveyor as well as the lateral distance between the two clamps and,therefore, the lateral distance between the two guide plates 54. To aidin the proper support and positioning of the plastic sheet as it isbeing fed in, the lateral guide plates 54 preferably have lower inwardlyextending sections 67 which can engage and support the outer edges ofthe incoming sheet, and the guide plates may be formed as full channels,each with upper inwardly extending section 68. To further help guide thesheet into place between the guide plates 54, downwardly curved metaltongue extensions 70 may be fixed to the incoming end of the extendingsection 67 of each guide plate, and extend over the curvature of theconveyor belt at the intake end 35.

[0021] After the operator has adjusted the lateral positions of theguide plates 54 during setup, a new plastic sheet to be fed is insertedbetween the guide plates 54 and pushed up under the guide wheels 60. Airpressure is then supplied to the air cylinders 64 to drive the guidewheels 60 into contact with the plastic sheet. The guide wheels 60 arepreferably positioned at the lateral edges of the plastic sheet,approximately at those portions of the plastic sheet that will ride onthe inward extensions 67 of the lateral guide plates 54. The guidewheels 60 press the plastic sheet against the top surface 39 of theconveyor to hold the plastic sheet in position so that it will not tendto wander laterally as it is being fed up the conveyor and to helpstabilize the plastic sheet against bunching or wrinkling while it is onthe conveyor.

[0022] With reference to FIG. 5, the plastic sheet exiting from thedischarge end 37 of the conveyor comes into engagement with and may besupported initially by a set of curved inner guide rods 74 which curvefrom a horizontal section 75 to a vertical section 76 that extendsdownwardly toward the trim press. A second, outer set of curved guiderods 78 extend from a generally horizontal section 79 spaced above theposition at which the plastic sheet exits the discharge end of theconveyor and curve outwardly and then downwardly to a vertical section80, with the vertical sections 80 of the guide rods 78 spaced slightlyoutwardly of the vertical section 76 of the guide rods 74 to hold theplastic sheet 11 between them as it is fed downwardly into properposition in the trim press. The guide rods 78 are preferably set atlateral positions at which they will ride between the formed parts 14 onthe sheet 11 or at the edges of the sheet to thereby provide somelateral guiding of the sheet into the trim press 12. The guide rods 74and 78 function similarly to and may be formed similarly to theconventional guide rods used at the top end of conventional canopy feedsystems.

[0023] As best shown in FIGS. 2 and 5, a limit switch 84 is mounted to across rod 85 which is itself mounted by brackets 86 and 87 to the frame.The limit switch 84 has a downwardly extending trip rod 88 which extendsbetween the outer guide rods 78 at the curved section of the guide rods.The trip rod 88 is outwardly movable to trip the limit switch 84 from anormally closed to an open position. A power line 90 extends from thelimit switch 84 to a control box 92 to supply power to and from thelimit switch, as explained further below. The trip rod 88 is mounted ata position spaced outwardly a selected distance from the discharge end37 of the conveyor at a position where it may be contacted by theplastic sheet material 11, as illustrated in FIG. 2. During feedingoperation, the conveyor belt 33 is driven by the motor 44 at a constantspeed until the plastic sheet that exits from the discharge end of theconveyor bulges outwardly a sufficient distance to contact the trip rod88 and displace it outwardly to switch the limit switch 84, turning offthe power to the motor 44 and stopping the conveyor. As the plasticsheet material 11 is then drawn downwardly into the trim press, thebulging section 94 of the plastic is drawn away from the trip rod 88,allowing the trip rod to return by spring action to its normal position,at which the switch 84 is closed, supplying power to the motor 44 againto drive the conveyor belt 33. A blower 95 may be mounted to the framebeneath the discharge end 37 of the conveyor and is positioned such thatthe outlet 96 of the blower is directed outwardly from the discharge endof the conveyor to blow the plastic sheet material exiting from theconveyor toward the outer guide rods 78 and toward the trip rod 88,helping to ensure that the maximum extent of the bulge 94 caused by theexcess of plastic sheet driven off of the conveyor is directed towardthe trip rod 88. It is understood that any other means for detectingthat the plastic sheet exiting from the conveyor has reached theselected position may be utilized in place of the trip rod 88 and limitswitch 84. Examples include light beam detectors and sonic and othertypes of proximity sensors.

[0024] In accordance with the invention, the conveyor belt 33 may alsobe driven at a constant speed that discharges plastic sheet from thedischarge end at a rate that corresponds to the average rate at whichplastic sheet is drawn into the trim press. In this mode of operation,utilization of the limit switch 84 is not necessary.

[0025] The positions of the inner guide rods 74 and the outer guide rods78 are preferably adjustable laterally to suit the size of the plasticsheet being fed and the positions of the formed parts 14 on the plasticsheets. As illustrated in FIG. 5, the inner guide rods 74 may be mountedto manually lockable clamps 97 which are laterally adjustable on a crossrod 98. The outer guide rods 78 are also preferably mounted for lateraladjustment to manually lockable clamps 99 mounted for sliding movementon the cross rod 85 and at the bottom ends of the guide rods to manuallylockable clamps 101 which are mounted for sliding movement on a crossrod 102 that is itself mounted to the frame.

[0026] If desired, a set of support wheels 105 may be mounted to theframe in a position to be rotated downwardly to support the apparatus 10when it is not in use and to be rotated out of the way (to the positionshown in FIG. 1) when the feeding apparatus is set up in position tofeed plastic sheet material to the trim press.

[0027] The feeding arrangement of the present invention allows anefficient control system to be used for coordinating the feeding of theplastic sheet by the feeding apparatus 10 with the drawing of a plasticsheet into the trim press 12. As illustrated in the simplified schematicdiagram of FIG. 6, electrical power from power mains 106 is supplied tothe control box 92 that encloses a main on/off switch 108 and a variablespeed motor controller 109. The control box 92 is connected by the lines90 to the limit switch 84 and by power lines 111 to the DC motor 44. Asuitable commercial controller is a Model KBMG-212D variable speed SCRControl from KB Electronics, Inc. The limit switch 84 is connected to arelay coil 115 which when energized closes relay contacts 116 to providepower through the controller 109 to the motor. Several push buttonswitches 118 may be connected in series with the limit switch 84 and arelocated at various positions to allow an operator to manually stop theconveyor. An adjustable potentiometer 120 connected to the controller109 allows the output voltage from the controller to be adjusted. Aswitch 121 may be connected to the controller to allow reversal of theoutput voltage to reverse the direction of the conveyor. As also shownin FIG. 6, the motor 124 for the blower 96 may be connected to the mainswitch 108 through an on-off switch 126. Fuses 128 and 129 are connectedin the power lines for overload protection. When sheet feeding is totake place, the operator closes the main switch 108, which suppliespower to the normally closed limit switch 84. As long as the limitswitch 84 remains closed, the variable speed drive 109 is activated. Theoutput power provided from the drive 109 to the motor 44 is adjusted bythe operator so that the speed of the conveyor belt 33 is such as toadvance an appropriate length of plastic sheet material before the limitswitch 84 is tripped as the sheet material engages the trip rod 88. Theappropriate length of plastic sheet material that is to be advanced bythe conveyor corresponds to the length of plastic sheet material that isdrawn into the trim press during each advancement step of a section ofplastic sheet material into the trim press cutting dies. The operatorcan simply adjust the speed of the drive 109 during operation to advanceor retard the speed of the conveyor until the right amount of plasticsheet is advanced during each cycle of the trim press.

[0028] It is understood that the invention is not confined to theparticular embodiments set forth herein as illustrative, but embracesall such forms thereof as come within the scope of the following claims.

What is claimed is:
 1. A canopy feed apparatus for a trim presscomprising: (a) an endless belt conveyor having a conveyor belt with atop facing side extending from an intake end to a discharge end and amotor connected to the belt to drive the belt, the conveyor mountedadjacent to a trim press to extend upwardly from horizontal from theintake end to the discharge end to feed the trim press with plasticsheet discharged from the discharge end; and (b) guides mounted at thedischarge end of the conveyor to guide plastic sheet discharged from theconveyor into the trim press.
 2. The apparatus of claim 1 furtherincluding a pair of guide wheels in position to selectively pressagainst a plastic sheet supported on a top facing side of the conveyorbelt at a position proximate to the intake end of the conveyor and apair of lateral guide plates in position above the top facing side ofthe conveyor belt to laterally position an incoming sheet and means formounting the guide wheels and the guide plates for adjustment of thelateral position of the guide wheels and the guide plates.
 3. Theapparatus of claim 2 wherein the means for mounting the guide wheels andguide plates include at least one mounting bar extending laterallybetween frame members above the top facing side of the conveyor belt, aclamp for each guide wheel and guide plate mounted for sliding movementon the mounting rod and including a locking mechanism by which the clampcan be locked in a selected lateral position, a guide wheel and a guideplate mounted to each clamp to move therewith in lateral adjustment. 4.The apparatus of claim 1 further including means for detecting a plasticsheet extending outwardly from the discharge end of the conveyor belt aselected distance and for controlling the motor of the conveyor to shutoff power to the motor when a section of plastic sheet exiting theconveyor extends the selected distance from the discharge end, and forsupplying power to the motor to drive the conveyor when the plasticsheet exiting from the conveyor does not extend the selected distanceoutwardly from the discharge end of the conveyor.
 5. The apparatus ofclaim 4 wherein the means for detecting includes a limit switch with atrip rod extending therefrom mounted such that the trip rod is spaced aselected distance from the discharge end of the conveyor in position tobe contacted by a section of plastic sheet discharged from the conveyor,the limit switch electrically connected to the motor for the conveyor toshut off power to the motor when a section of plastic sheet is incontact with the trip rod so as to trip the limit switch, and to supplypower to the motor to drive the conveyor when the plastic sheet exitingfrom the conveyor is out of contact with the trip rod.
 6. The apparatusof claim 4 further including a blower mounted beneath the discharge endof the conveyor to blow air outwardly to push the plastic sheet exitingfrom the conveyor away from the discharge end of the conveyor.
 7. Theapparatus of claim 1 wherein the conveyor belt is formed of a flexibleplastic material having a selected coefficient of friction with regardto plastic sheet material to be supported by the conveyor.
 8. Theapparatus of claim 1 wherein the top facing surface of the conveyorextending at an angle of approximately 300 from horizontal from theintake end to the discharge end of the conveyor.
 9. The apparatus ofclaim 1 wherein the guides comprise curved guide rods extending aboveand below the position of plastic sheet exiting from the discharge endof the conveyor and formed to guide the plastic sheet to a positionwhere it is fed into the trim press.
 10. The apparatus of claim 9further including means for adjustably setting the lateral positions ofthe curved guide rods.
 11. A canopy feed apparatus for a trim presscomprising: (a) frame members forming a frame; (b) an endless beltconveyor mounted to the frame having a conveyor belt with a top facingside extending from an intake end to a discharge end and a motorconnected to the belt to drive the belt, the conveyor mounted to theframe to extend upwardly from horizontal from the intake end to thedischarge end when the feed apparatus is installed to feed a trim press;(c) a pair of lateral guide plates positioned above the top facing sideof the conveyor belt proximate to the intake end of the conveyor tolaterally position an incoming sheet; and (d) means for mounting theguide plates for adjustment of the lateral position of the guide plates.12. The apparatus of claim 11 including a pair of guide wheelspositioned to selectively press against a plastic sheet supported on atop facing side of the conveyor belt at a position proximate to theintake end of the conveyor and means for mounting the guide wheels tothe frame for adjustment of the lateral position of the guide wheels.13. The apparatus of claim 12 wherein the means for mounting the guidewheels and guide plates include at least one mounting bar extendinglaterally between frame members above the top facing side of theconveyor belt, a clamp for each guide wheel and guide plate mounted forsliding movement on the mounting rod and including a locking mechanismby which the clamp can be locked in a selected lateral position, a guidewheel and a guide plate mounted to each clamp to move therewith inlateral adjustment.
 14. The apparatus of claim 13 further including anair cylinder connected to each guide wheel and responsive to airpressure supplied to the air cylinder to press the guide wheel connectedthereto against the top side of the conveyor belt.
 15. The apparatus ofclaim 13 wherein there are a pair of mounting bars that extend laterallybetween frame members above the top facing side of the conveyor belt,the pair of lateral guide plates and guide wheels mounted to themounting bars for sliding lateral movement adjacent to the top facingside of the conveyor belt.
 16. The apparatus of claim 11 furtherincluding means for detecting a plastic sheet extending outwardly fromthe discharge end of the conveyor belt a selected distance and forcontrolling the motor of the conveyor to shut off power to the motorwhen a section of plastic sheet exiting the conveyor extends theselected distance from the discharge end, and for supplying power to themotor to drive the conveyor when the plastic sheet exiting from theconveyor does not extend the selected distance outwardly from thedischarge end of the conveyor.
 17. The apparatus of claim 16 wherein themeans for detecting includes a limit switch with a trip rod extendingtherefrom mounted such that the trip rod is spaced a selected distancefrom the discharge end of the conveyor in position to be contacted by asection of plastic sheet discharged from the conveyor, the limit switchelectrically connected to the motor for the conveyor to shut off powerto the motor when a section of plastic sheet is in contact with the triprod so as to trip the limit switch, and to supply power to the motor todrive the conveyor when the plastic sheet exiting from the conveyor isout of contact with the trip rod.
 18. The apparatus of claim 16 furtherincluding a blower mounted beneath the discharge end of the conveyor toblow air outwardly to push the plastic sheet exiting from the conveyoraway from the discharge end of the conveyor.
 19. The apparatus of claim11 wherein the conveyor belt is formed of a flexible plastic materialhaving a selected coefficient of friction with regard to plastic sheetmaterial to be supported by the conveyor.
 20. The apparatus of claim 11wherein the top facing surface of the conveyor extending at an angle ofapproximately 30° from horizontal from the intake end to the dischargeend of the conveyor.
 21. The apparatus of claim 11 wherein the guidescomprise curved guide rods extending above and below the position ofplastic sheet exiting from the discharge end of the conveyor and formedto guide the plastic sheet to a position where it is fed into the trimpress.
 22. The apparatus of claim 21 further including means foradjustably setting the lateral positions of the curved guide rods.
 23. Acanopy feed apparatus for a trim press comprising: (a) frame membersforming a frame; (b) an endless belt conveyor mounted to the framehaving a conveyor belt with a top facing side extending from an intakeend to a discharge end and a motor connected to the belt to drive thebelt; and (c) means for detecting a plastic sheet extending outwardlyfrom the discharge end of the conveyor belt a selected distance and forcontrolling the motor of the conveyor to shut off power to the motorwhen a section of plastic sheet exiting the conveyor extends at leastthe selected distance from the discharge end, and for supplying power tothe motor to drive the conveyor when the plastic sheet exiting from theconveyor does not extend the selected distance outwardly from thedischarge end of the conveyor.
 24. The apparatus of claim 23 includingguide wheels in position to selectively press against a plastic sheetsupported on a top facing side of the conveyor belt at a positionproximate to the intake end of the conveyor and a pair of lateral guideplates in position above the top facing side of the conveyor tolaterally position an incoming sheet, and means for mounting the guidewheels and the guide plates to the frame for adjustment of the lateralposition of the guide wheels and the guide plates.
 25. The apparatus ofclaim 24 wherein the means for mounting the guide wheels and guideplates to the frame includes at least one mounting bar extendinglaterally between frame members above the top facing side of theconveyor belt, a clamp for each guide wheel and guide plate mounted forsliding movement on the mounting rod and including a locking mechanismby which the clamp can be locked in a selected lateral position, a guidewheel and a guide plate mounted to each clamp to move therewith inlateral adjustment.
 26. The apparatus of claim 23 wherein the means fordetecting includes a limit switch with a trip rod extending therefrommounted such that the trip rod is spaced a selected distance from thedischarge end of the conveyor in position to be contacted by a sectionof plastic sheet discharged from the conveyor, the limit switchelectrically connected to the motor for the conveyor to shut off powerto the motor when a section of plastic sheet is in contact with the triprod so as to trip the limit switch, and to supply power to the motor todrive the conveyor when the plastic sheet exiting from the conveyor isout of contact with the trip rod.
 27. The apparatus of claim 23 furtherincluding a blower mounted beneath the discharge end of the conveyor toblow air outwardly to push the plastic sheet exiting from the conveyoraway from the discharge end of the conveyor.
 28. The apparatus of claim23 wherein the conveyor belt is formed of a flexible plastic materialhaving a selected coefficient of friction with regard to plastic sheetmaterial to be supported by the conveyor.
 29. The apparatus of claim 23wherein the frame is mounted adjacent to a trim press with the topfacing surface of the conveyor extending at an angle of approximately30° from horizontal from the intake end to the discharge end of theconveyor.
 30. The apparatus of claim 23 further including curved guiderods mounted to the frame and extending above and below the position ofplastic sheet exiting from the discharge end of the conveyor and formedto guide the plastic sheet to a position where it may be fed into a trimpress.
 31. The apparatus of claim 30 further including means foradjustably setting the lateral positions of the guide rods.
 32. A methodof feeding continuous plastic sheet material to a trim press which trimsformed parts from the surrounding plastic sheet comprising: (a)supporting a portion of the plastic sheet to be trimmed on the surfaceof a conveyor belt of an endless belt conveyor; (b) operating theconveyor to drive the belt in a direction from an intake end of theconveyor to a discharge end to draw the plastic sheet supported on theconveyor toward the discharge end and to discharge a section of plasticsheet from the discharge end of the conveyor and then stopping theconveyor belt; (c) allowing the trim press to draw a section of theplastic sheet discharged from the conveyor into the trim press fortrimming; and (d) then again operating the conveyor to draw the plasticsheet material with the conveyor belt to discharge another section ofplastic sheet material from the discharge end of the conveyor and thenstopping the conveyor belt.
 33. The method of claim 32 wherein steps (c)and (d) are repeated.
 34. The method of claim 35 further includingguiding the plastic sheet supported on the conveyor belt with guideplates positioned adjacent to lateral side edges of the plastic sheet tolaterally locate the plastic sheet on the conveyor in proper position tobe fed to the trim press.
 35. The method of claim 34 further includingpressing the plastic sheet against the conveyor belt with guide wheelsto hold the plastic sheet in place on the conveyor belt as the conveyoris operated.
 36. The method of claim 36 further including detecting whena selected length of section of plastic sheet has been discharged fromthe conveyor during operation of the conveyor and then stopping theconveyor.
 37. A method of feeding continuous plastic sheet material to atrim press which trims formed parts from the surrounding plastic sheetcomprising: (a) supporting a portion of the plastic sheet to be trimmedon the surface of a conveyor belt of an endless belt conveyor; (b)operating the conveyor to drive the belt in a direction from an intakeend of the conveyor to a discharge end to draw the plastic sheetsupported on the conveyor toward the discharge end and to discharge asection of plastic sheet from the discharge end of the conveyor whileallowing the trim press to draw a section of the plastic sheetdischarged from the conveyor, and driving the belt at a speed such thatthe rate at which the plastic sheet is discharged from the conveyorcorresponds to the average rate which plastic sheet is drawn into thetrim press for trimming.
 38. The method of claim 37 further includingguiding the plastic sheet supported on the conveyor belt with guideplates positioned adjacent to lateral side edges of the plastic sheet tolaterally locate the plastic sheet on the conveyor in proper position tobe fed to the trim press.
 39. The method of claim 38 further includingpressing the plastic sheet against the conveyor belt with guide wheelsto hold the plastic sheet in place on the conveyor belt as the conveyoris operated.